1. Field of the Invention
This invention in general relates to a magnetically actuated reed switch and more particularly to a magnetically actuated reed switch as used in timing systems for fuel injection internal combustion engines.
2. Prior Art
In the ignition systems of motor vehicles, more particularly in the distributor units, there has been attached to the distributor shaft an annular magnet having a plurality of angularly spaced alternating poles. A single reed switch is actuated by each magnetic pole as it passes by the switch, thereby causing an electrical circuit to operate and generate a signal for firing each spark plug. In each system there is required that either the number of poles of the magnet or the number of separate switches equal the number of pulses required per revolution of the distributor shaft.
The above system was further improved to provide a more definable electrical signal to each spark plug by encasing the reed switch with a copper bushing. The bushing forms a shorted turn to magnetic signals of higher frequency than that generated by the rotating magnet therefore reducing the sensitivity of the reed switch. This system still requires that the total number of either the magnets or switches equal the total number of pulses required per revolution of the distributor shaft.
Another system for use in an ignition distributor apparatus utilizes a stationary magnet spaced from a stationary switch and having a rotating shunt member pass between the magnet and the switch. The system requires a magnet and a switch combination for each pulse generator and the configuration of the shunt provides the timing of the signal generated.
Another system teaches a single movable magnet and a plurality of switches, one switch for each output signal line. As the magnet rotates past each switch, the switch is actuated and an electrical signal is generated. In this system there must be a number of magnets equal to the desired number of signals if there is one switch, or in the alternative with one magnet, there must be a plurality of switches equal to the number of signals desired.